The de novo synthesis of glucagon receptors can be induced in transformed MDCK cells by butyrate (a known differentiation inducer) and prostaglandin E1 (which elevates cAMP in these cells) and RO20-1724 (an inhibitor of phospho-diesterase). However, the concentration dependence of induction for both prostaglandin E1 and R020-1724 do not parallel their ability to elevate cAMP levels. In fact, higher concentrations of cAMP actually inhibit the induction process, although there is no effect of high cAMP concentrations on glucagon responsiveness of the parental line. The data suggests that high levels of cAMP inhibit the synthesis of glucagon receptors and that important differences in the newly synthesized receptor system may provide insight into the consequences of viral transformation.